A social network is defined as a network that horizontally extends from a user on the basis of individual identities on the Internet. As a network configured by adding other people around ‘me’, the social network includes different features from the conventional community. The social network is well appreciated in social relationships in a sense that personal value evaluation and personal connections have a great effect on human life. Further, the social network has rapidly spread since it is a very useful tool for creating individual personal connections.
A social network service is provided in such a manner that a user inputs user information to register to a specific site, and thereafter configures a network of users by selecting users for making personal connections or by receiving a recommendation of another user.
However, the aforementioned method has a risk that user information may be leaked when the user inputs the user information to register to the site. Also, the user experiences inconvenience when directly selecting other users to configure the network. In addition, there is a problem in that even if a different user is recommended, whether the recommended user is a right person cannot be known since there is no correct information on the different user.
Recently, with the growing demand on contents that can be purchased by using a user terminal, contents to be provided to the user terminal also tend to increase. It becomes difficult for the user terminal to find desired contents from a contents server due to the rapid increase of the contents. Of course, for user convenience, the contents server may show the contents by classifying the contents according to content type or show the contents in a descending order of sales. However, there is a high possibility that this method is not suitable for users' preference or taste. Therefore, the user inconveniently checks for a large amount of contents one by one to purchase desired contents, which may decrease a user's purchase desire.